The broad objective of this research project is a correlation between certain aspects of visual behavior (learning and memory of brightness and pattern discriminations, measurements of visual fields by perimetry, data on thresholds and acuity) and the responses of single neurons in visual centers of cortex and midbrain. These studies will be conducted in cats before and after lesions in various visual centers of the brain, whose anatomical organization is known, and after experimentally induced amblyopia exanopsia.